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Look at the first two equations:
x + y - z = 11
2x + 2y - z = 19
If we multiply the first one by 2, we can subtract it the second one and have a value for z.
2x + 2y - 2z = 22
-(2x + 2y - z = 19)
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-z = 3
z = -3
Now plug this value into the first and third equations:
x + y + 3 = 11
x - 5y + 9 = -25
Subtract the second one of these from the first:
6y - 6 = 36
6y = 42
y = 7
Then plug this back into the first equation along with the value we found for z:
x + 7 + 3 = 11
x = 1
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#22.
5 * 10^(3-7)
5 * 10^(-4)
5 / 10000
.0005
#23
(x^2 - 25) / (2x + 10)
Factor the numerator and it becomes (x+5)(x-5)
Then factor a 2 out of the denominator and it becomes 2(x+5)
Now, we have (x+5) on both top and bottom, so it will cancel, leaving us with
(x-5)/2
Valerie
Veritas Help
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